Image forming apparatus

Abstract

To improve the visibility of a connector while maintaining the rigidity of a fixing unit.SOLUTION: An image forming apparatus 100 comprises: image carriers 1, 5; a light detection device 7 that detects a pattern image formed on the image carriers; and a fixing unit 17 (170) that fixes the light detection device. The light detection device includes a substrate 201; light emitting elements 73, 74 and light receiving elements 71, 72 provided on a first surface 201a of the substrate, and a connector 205 provided on a second surface 201b opposite to the first surface of the substrate. The fixing unit includes a reference surface 17b (170b) in contact with the second surface of the substrate. In an insertion and withdrawal direction of a cable 300 connected to the connector, a first thickness h_u of a part of a portion of the fixing unit in contact with the second surface from the reference surface, is smaller than a second thickness H of a portion of the fixing unit not in contact with the second surface from the reference surface.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus having a sensor attached to a mounting member, a light detection device including a sensor and a mounting member for the sensor, and a mounting member to which the sensor is attached. [Background technology]

[0002] Conventionally, color image forming devices, such as copiers, printers, and facsimiles, that employ a tandem system correct misregistration and density misregistration for each color. To achieve this, the image forming units for each color form color misregistration detection patterns and density detection patterns, detect the amount of color misregistration and density misregistration, and correct the color misregistration and density misregistration. The color misregistration detection patterns and density detection patterns are detected by a photodetector (optical sensor) located near the intermediate transfer belt. The photodetector has a light-emitting element and a light-receiving element. The light-emitting element illuminates the intermediate transfer belt and the color misregistration detection patterns and density detection patterns formed on the intermediate transfer belt. The light-receiving element receives reflected light from the intermediate transfer belt and the color misregistration detection patterns and density detection patterns. The amount of color misregistration and density misregistration is detected based on the difference in the amount of reflected light between the intermediate transfer belt and the color misregistration detection patterns and the difference in the amount of reflected light between the intermediate transfer belt and the density detection patterns.

[0003] As image forming devices become smaller, there is a demand for smaller optical components in photodetectors. Patent Document 1 discloses a photodetector that is smaller in size by directly mounting a light-emitting element and a light-receiving element on a circuit board and shortening the distance between the elements compared to conventional configurations that use components (lead components) mounted through a lead frame. By mounting control circuit components, a connector for connecting to an external control device, and other components on the side opposite to the side on which the light-emitting element and the light-receiving element are directly mounted, the circuit board can be made smaller, and the photodetector can be made even smaller.

[0004] The photodetector is fixed to the image forming apparatus facing the intermediate transfer belt. From the standpoint of ease of assembly for fixing the photodetector to the image forming apparatus, the photodetector is fixed to a fixing unit in advance, and the fixing unit with the photodetector fixed thereto is then fixed to the image forming apparatus. Furthermore, the photodetector is fixed to the image forming apparatus so that its focus is on the surface of the intermediate transfer belt in order to detect the color misregistration detection pattern and density detection pattern formed on the intermediate transfer belt. Therefore, when fixing the fixing unit to the image forming apparatus, it is necessary to prevent the fixing unit from bending or deforming, causing the distance between the photodetector and the intermediate transfer belt to deviate from the predetermined distance. Therefore, the thickness of the fixing unit is increased to increase the rigidity of the fixing unit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-208266 Summary of the Invention [Problem to be solved by the invention]

[0006] However, a circuit board with a connector on the side opposite the side on which the optical element and the light-receiving element are provided is fixed to the fixing unit by inserting the connector into a through-hole provided in the fixing unit. Increasing the thickness of the fixing unit to increase the rigidity of the fixing unit results in a deeper through-hole. When connecting a cable to a connector located deep inside a deep through-hole, the connector is difficult to see. Furthermore, when connecting the cable to the connector, the hand holding the cable interferes with the fixing unit, reducing the efficiency of the connection work.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve the visibility of the connector of a sensor and to improve the workability of connecting the connector and the cable. [Means for solving the problem]

[0008] An image forming apparatus according to an embodiment of the present invention comprises: an image carrier; a sensor for detecting a pattern image formed on the image carrier; a mounting member to which the sensor is attached; Equipped with The sensor A substrate; a light-emitting element provided on a first surface of the substrate; a light receiving element provided on the first surface of the substrate; a connector provided on a second surface of the substrate opposite the first surface; Equipped with The mounting member is a third surface having an opening into which the connector of the sensor is inserted; a fourth surface perpendicular to the third surface and parallel to the longitudinal direction of the mounting member; a part of the fourth surface of the mounting member is cut out so that the connector can be easily seen when viewed from one direction perpendicular to the longitudinal direction of the mounting member and parallel to the first surface of the sensor attached to the mounting member; The width of the cutout portion of the fourth surface in the longitudinal direction of the mounting member is wider than the width of the connector inserted into the opening in the longitudinal direction of the mounting member. It is characterized by: An optical detection device according to an embodiment of the present invention comprises: a substrate; a light-emitting element provided on a first surface of the substrate; a light-receiving element provided on the first surface of the substrate; and a connector provided on a second surface of the substrate opposite to the first surface; a sensor comprising: a mounting member to which the sensor is attached, The mounting member is a third surface having an opening into which the connector of the sensor is inserted; a fourth surface perpendicular to the third surface and parallel to the longitudinal direction of the mounting member; a part of the fourth surface of the mounting member is cut out so that the connector can be easily seen when viewed from one direction perpendicular to the longitudinal direction of the mounting member and parallel to the first surface of the sensor attached to the mounting member; The width of the cutout portion of the fourth surface in the longitudinal direction of the mounting member is wider than the width of the connector inserted into the opening in the longitudinal direction of the mounting member. The mounting member according to one embodiment of the present invention comprises: a substrate; a light-emitting element provided on a first surface of the substrate; a light-receiving element provided on the first surface of the substrate; and a connector provided on a second surface of the substrate opposite to the first surface; A mounting member to which a sensor comprising: a third surface having an opening for inserting the connector of the sensor; a fourth surface perpendicular to the third surface and parallel to the longitudinal direction of the mounting member; a cutout portion of the fourth surface of the mounting member so that the connector can be easily seen when viewed from one direction perpendicular to the longitudinal direction of the mounting member and parallel to the first surface of the sensor attached to the mounting member; and and The width of the cutout portion of the fourth surface in the longitudinal direction of the mounting member is wider than the width of the connector to be inserted into the opening in the longitudinal direction of the mounting member. [Effects of the Invention]

[0009] According to the present invention, the visibility of the connector of the sensor can be improved, and the workability of connecting the connector and the cable can be improved. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] FIG. 2 is a block diagram showing the electrical configuration of the image forming apparatus. [Figure 4] FIG. 4 is a diagram showing a color misregistration detection pattern image. [Figure 5] 10A and 10B are diagrams showing output waveforms of a pattern sensor that detects a color misregistration detection pattern image. [Figure 6] FIG. 4 is a diagram showing a density detection pattern image. [Figure 7] FIG. 10 is a diagram showing an output waveform of a pattern sensor that detects a first density detection pattern image. [Figure 8] FIG. 10 is a diagram showing an output waveform of a pattern sensor that detects a second density detection pattern image. [Figure 9] FIG. 10 is a diagram showing a fixed unit to which a pattern sensor is attached. [Figure 10] FIG. 10 is a diagram showing a fixing unit according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. [Example]

[0012] (Image forming device) FIG. 1 is a cross-sectional view of an image forming apparatus 100. The image forming apparatus 100 is a printer that uses electrophotography to form a color image on a recording medium S, such as paper (sheet), using multiple color toners. The image forming apparatus 100 has four image forming units 101 (101Y, 101M, 101C, and 101K). The image forming unit 101Y forms a yellow image using yellow toner. The image forming unit 101M forms a magenta image using magenta toner. The image forming unit 101C forms a cyan image using cyan toner. The image forming unit 101K forms a black image using black toner. The subscripts Y, M, C, and K in the reference symbols represent yellow, magenta, cyan, and black, respectively. In the following description, the subscripts Y, M, C, and K in the reference symbols may be omitted unless otherwise necessary. The four image forming units 101 have the same structure except for the color of the developer (toner).

[0013] The image forming unit 101 has a photosensitive drum 1 as a photosensitive member. Around the photosensitive drum 1, a charger 8, an optical scanning device (laser writing unit) 15, a developing device 16, a primary transfer roller 10, and a drum cleaning device 9 are arranged. An endless intermediate transfer belt (image carrier) 5 is arranged below the photosensitive drum 1. The intermediate transfer belt 5 rotates and moves in a moving direction R1. The primary transfer roller 10 is arranged opposite the photosensitive drum 1 via the intermediate transfer belt 5. The primary transfer roller 10 transfers the toner image on the photosensitive drum 1 to the intermediate transfer belt 5. The secondary transfer roller 4 is arranged opposite the belt support roller 3 via the intermediate transfer belt 5. The secondary transfer roller 4 transfers the toner image on the intermediate transfer belt 5 to a recording medium S.

[0014] A feed cassette 20 that stores recording media S such as paper (sheets) is disposed at the bottom of the image forming apparatus 100. The recording media S is fed from the feed cassette 20 by a pickup roller 19 and transported to a secondary transfer roller 4 by a feed roller 22, a transport roller 23, and a registration roller 24. A transport belt 12 and a fixing device 13 are disposed downstream of the secondary transfer roller 4 in the transport direction CD of the recording media S. The fixing device 13 fixes the toner image onto the recording media S.

[0015] Next, we will explain the image formation process of the image forming apparatus 100. Since the image formation process is the same in the four image forming units 101, we will explain the image formation process in image forming unit 101Y, which forms a yellow toner image. We will not explain the image formation processes in image forming unit 101M, which forms a magenta toner image, image forming unit 101C, which forms a cyan toner image, and image forming unit 101K, which forms a black toner image.

[0016] The photosensitive drum 1Y rotates in the direction indicated by arrow R2 in FIG. 1. The charger 8Y uniformly charges the surface of the photosensitive drum 1Y to a predetermined potential. The optical scanning device 15Y emits a laser beam (light beam) modulated according to yellow image information from a semiconductor laser (not shown) as a light source, forming an electrostatic latent image on the uniformly charged surface of the photosensitive drum 1Y. The developing device 16Y develops the electrostatic latent image with yellow toner (developer) to form a yellow toner image. The primary transfer roller 10Y transfers the yellow toner image on the photosensitive drum 1Y onto the intermediate transfer belt 5. Any toner remaining on the photosensitive drum 1Y after the primary transfer is collected by a drum cleaning device 9Y.

[0017] Similarly, the magenta toner image formed by image forming unit 101M is transferred onto the yellow toner image on the intermediate transfer belt 5 with high precision, superimposed thereon. Thereafter, a cyan toner image and a black toner image are sequentially transferred onto the magenta toner image on the intermediate transfer belt 5, superimposed thereon. As a result, the four color toner images are sequentially superimposed on the intermediate transfer belt 5, forming a color toner image 6.

[0018] The recording medium S transported from the feeding cassette 20 is transported to the secondary transfer roller 4 by the registration roller 24 so that the leading edge of the color toner image 6 on the intermediate transfer belt 5 coincides with the leading edge of the recording medium S. The color toner image 6 on the intermediate transfer belt 5 is transferred all at once to the recording medium S by the secondary transfer roller 4. Any toner remaining on the intermediate transfer belt 5 after the secondary transfer is collected by an intermediate transfer belt cleaner 14. The recording medium S onto which the toner image has been transferred is transported by the transport belt 12 to the fixing device 13. The fixing device 13 applies heat and pressure to the recording medium S to fix the toner image to the recording medium S. The recording medium S on which the image has been formed is discharged out of the image forming apparatus 100 by a fixing exit roller 26 and a discharge roller 27.

[0019] The color toner image 6 formed on the intermediate transfer belt 5 may become misaligned due to manufacturing variations in the optical scanning device 15 and the photosensitive drum 1, deformation of parts due to temperature rise, and variations in the transport of the intermediate transfer belt 5. The color misalignment occurs when the yellow toner image, magenta toner image, cyan toner image, and black toner image are misaligned. The color misalignment is corrected based on the detection results obtained by detecting a color misalignment detection pattern formed on the intermediate transfer belt 5 with a pattern sensor (optical sensor) 7.

[0020] Furthermore, image density varies depending on the temperature and humidity conditions of the environment in which the image forming apparatus 100 is used and the frequency of use of each color. Fluctuations in image density cause density deviations, in which the image density deviates from a predetermined density. The density deviations are corrected by controlling the optical scanning device 15, the developing device 16, and the photosensitive drum 1 based on the detection results obtained by detecting the density detection pattern formed on the intermediate transfer belt 5 using the pattern sensor 7.

[0021] (pattern sensor) A pattern sensor 7 serving as a light detection device is disposed near the intermediate transfer belt 5. The pattern sensor 7 is fixed to a fixing unit 17 with screws 21 (FIG. 9). The pattern sensor 7 is fixed to the image forming apparatus 100 by the fixing unit 17 so that the distance between the pattern sensor 7 and the intermediate transfer belt 5 is a predetermined distance so that the pattern sensor 7 is focused on the surface of the intermediate transfer belt 5. The pattern sensor 7 detects the density detection patterns and color misregistration detection patterns for each color formed on the intermediate transfer belt 5 at predetermined timing. Density correction and color misregistration correction are performed based on the detection results of the pattern sensor 7.

[0022] 2 is an explanatory diagram of the pattern sensor 7. The pattern sensor 7 has a circuit board (hereinafter referred to as board) 201. A first photodiode (hereinafter referred to as first PD) 71 and a second photodiode (hereinafter referred to as second PD) 72 are provided on a surface (first surface) 201a of the board 201 as light receiving elements. A first light emitting diode (hereinafter referred to as first LED) 73 and a second light emitting diode (hereinafter referred to as second LED) 74 are further provided on the surface 201a of the board 201 as light emitting elements. The first PD 71, the second PD 72, the first LED 73, and the second LED 74 are surface-mounted elements and are arranged on one board 201.

[0023] A housing 203 is attached to a surface 201a of the substrate 201, covering the first PD 71, the second PD 72, the first LED 73, and the second LED 74. The housing 203 is provided with a lens group 204 including a plurality of lenses 204a, 204b, 204c, and 204d. The lenses 204a, 204b, 204c, and 204d are disposed near the first PD 71, the second PD 72, the first LED 73, and the second LED 74, respectively. The housing 203 is provided with light guide paths between the lenses 204a, 204b, 204c, and 204d and the first PD 71, the second PD 72, the first LED 73, and the second LED 74, respectively.

[0024] Light emitted from the first LED 73, which serves as a specularly reflected light emitter, passes through a light guide path in the housing 203 and a lens 204c, traveling in the direction of the optical axis (dotted line in FIG. 2), and is irradiated onto the intermediate transfer belt 5. The specularly reflected light specularly reflected by the intermediate transfer belt 5 passes through the lens 204a and a light guide path in the housing 203, and is incident on the first PD 71, which serves as a specularly reflected light receiver (specular reflection color shift detection light receiver, specular reflection density detection light receiver). As shown in FIG. 2, the first LED 73 and the first PD 71 are positioned so that the angle of incidence and the angle of reflection of the light from the first LED 73 with respect to the intermediate transfer belt 5 are equal. The first PD 71 functions as a light receiving unit that receives specularly reflected light from the light emitted from the first LED 73 to the intermediate transfer belt 5 and reflected by the intermediate transfer belt 5.

[0025] Meanwhile, light emitted from the second LED 74, which serves as a diffusely reflected light emitter, passes through a light guide path within the housing 203 and a lens 204d, traveling in the direction of the optical axis (solid line in FIG. 2), and is irradiated onto the intermediate transfer belt 5. The diffusely reflected light that is diffusely reflected by the intermediate transfer belt 5 passes through the lens 204b and the light guide path within the housing 203 and is incident on the second PD 72, which serves as a diffusely reflected light receiver (diffuse reflection concentration detection light receiver). As shown in FIG. 2, the second LED 74 and the second PD 72 are positioned so that the angle of incidence of the light from the second LED 74 with respect to the intermediate transfer belt 5 is not equal to the angle of reflection of the diffusely reflected light. The second PD 72 functions as a light receiving means that receives the diffusely reflected light of the light that is emitted from the second LED 74 to the intermediate transfer belt 5 and reflected by the intermediate transfer belt 5.

[0026] A connector 205, a control integrated circuit (hereinafter referred to as a control IC) 207, and other mounted components 206 are provided on a back surface (second surface) 201b of the substrate 201 opposite to the front surface 201a. The control IC 207 has a core chip, which is an integrated circuit, connected to the substrate 201 by wire bonding using a chip-on-board method. To protect the core chip and the wire bonding, a sealing resin is applied to the control IC 207. The control IC 207 controls the operations of the first PD 71, the second PD 72, the first LED 73, and the second LED 74, which are optical elements.

[0027] A connector 205 of the pattern sensor 7 is connected to a connector 301 of a cable 300. The pattern sensor 7 is electrically connected to a CPU 109 (FIG. 3) that controls the entire image forming apparatus 100 via the cable 300 connected to the connector 205. A control IC 207 communicates with the CPU 109 and controls the amount of light emitted by the first LED 73 and the second LED 74. The other mounted components 206 include, for example, a capacitor for stabilizing the power supplied to the control IC 207. The substrate 201 is provided with a first positioning hole 202a and a second positioning hole 202b, which are openings through which screws 21 (FIG. 9) that fix the pattern sensor 7 to the fixing unit 17 are inserted.

[0028] (Electrical configuration of image forming apparatus) FIG. 3 is a block diagram showing the electrical configuration of the image forming apparatus 100. The image forming apparatus 100 includes a CPU 109, a ROM 111, and an image formation control unit 120 as control means. A cable 300 electrically connects the pattern sensor 7 to the CPU 109. The cable 300 includes signal lines. The CPU 109 outputs a first light-emitting signal L1 and a second light-emitting signal L2 to the control IC 207 to control the illumination of the first LED 73 and the second LED 74 of the pattern sensor 7. The pattern sensor 7 converts the amounts of light received by the first PD 71 and the second PD 72, which receive reflected light from the intermediate transfer belt 5 or a toner pattern formed on the intermediate transfer belt 5, into voltages and outputs the voltages as a first detection signal P1 and a second detection signal P2. The first detection signal P1 and the second detection signal P2 are converted from analog to digital by an analog-to-digital converter (hereinafter referred to as an A / D converter) 110 built into the CPU 109 and input into the CPU 109.

[0029] The image forming control unit 120 has an optical scanning device control unit 112, a developing unit control unit 113, a photosensitive drum control unit 114, and an intermediate transfer belt control unit 115. The optical scanning device control unit 112 controls the optical scanning device 15. The developing unit control unit 113 controls the developing unit 16. The photosensitive drum control unit 114 controls the photosensitive drum 1. The intermediate transfer belt control unit 115 controls the intermediate transfer belt 5. The CPU 109 is electrically connected to the optical scanning device control unit 112, the developing unit control unit 113, the photosensitive drum control unit 114, the intermediate transfer belt control unit 115, and the ROM 111.

[0030] The CPU 109 controls the entire image forming apparatus 100 in accordance with various commands. The CPU 109 executes image forming operations in accordance with programs stored in the ROM 111. The CPU 109 controls the optical scanning device 15, the developing device 16, the photosensitive drum 1, and the intermediate transfer belt 5 via the image formation control unit 120, and forms a toner image on the intermediate transfer belt 5. The CPU 109 also forms a toner pattern for toner concentration detection (hereinafter referred to as a concentration detection pattern image) on the intermediate transfer belt 5 in accordance with the toner concentration detection image data stored in the ROM 111. The CPU 109 also forms a toner pattern for color misregistration detection (hereinafter referred to as a color misregistration detection pattern image) on the intermediate transfer belt 5 in accordance with the color misregistration detection image data stored in the ROM 111.

[0031] When detecting the amount of color misregistration, the CPU 109 turns on the first LED 73 of the pattern sensor 7. The first LED 73 illuminates the intermediate transfer belt 5 and the color misregistration detection pattern image formed on the intermediate transfer belt 5. The first PD 71 receives light reflected from the intermediate transfer belt 5 and the color misregistration detection pattern image formed on the intermediate transfer belt 5, and outputs a first detection signal P1 to the A / D converter 110. The A / D converter 110 converts the first detection signal P1 from an analog signal to a digital signal (digital value). The CPU 109 detects the amount of color misregistration from the digital signal of the first detection signal P1. The CPU 109 calculates the amount of correction for the amount of color misregistration based on the amount of color misregistration (detection result). The CPU 109 corrects the amount of color misregistration based on the calculated correction amount.

[0032] When detecting the toner concentration, the CPU 109 turns on the first LED 73 and the second LED 74 of the pattern sensor 7. The first LED 73 and the second LED 74 illuminate the intermediate transfer belt 5 and the concentration detection pattern image formed thereon. The first PD 71 and the second PD 72 receive light reflected from the intermediate transfer belt 5 and the concentration detection pattern image formed thereon, and output a first detection signal P1 and a second detection signal P2 to the A / D converter 110. The A / D converter 110 converts the first detection signal P1 and the second detection signal P2 from analog signals to digital signals (digital values). The CPU 109 detects the toner concentration level from the digital signals of the first detection signal P1 and the second detection signal P2. The CPU 109 calculates a toner concentration correction amount based on the toner concentration level (detection result). The CPU 109 corrects the toner concentration based on the calculated correction amount.

[0033] (Color misregistration detection pattern image) Next, a description will be given of the color misregistration detection pattern image formed on the intermediate transfer belt 5 when the CPU 109 detects the amount of color misregistration. FIG. 4 is a diagram showing a color misregistration detection pattern image 401. The color misregistration detection pattern image 401 includes two sets of toner patterns of yellow (Y), magenta (M), cyan (C), and black (K). One set of toner patterns of yellow (Y), magenta (M), cyan (C), and black (K) is inclined at 45° with respect to the movement direction R1 of the intermediate transfer belt 5. Another set of toner patterns of yellow (Y), magenta (M), cyan (C), and black (K) is inclined at -45° with respect to the movement direction R1 of the intermediate transfer belt 5.

[0034] FIG. 5 shows the output waveform of the pattern sensor 7 that detected the color misregistration detection pattern image 401. The non-pattern area NP, where the background of the intermediate transfer belt 5 is visible, has a high reflectivity on the surface of the intermediate transfer belt 5, resulting in a high read level of the first detection signal P1 output from the first PD 71 that receives specularly reflected light. On the other hand, the pattern-forming area, where yellow (Y), magenta (M), cyan (C), and black (K) pattern images are formed, has a low reflectivity due to the toner, resulting in a low read level of the first detection signal P1 output from the first PD 71 that receives specularly reflected light. Therefore, as shown in FIG. 5, the amount of color misregistration can be detected by detecting the positions of the yellow (Y), magenta (M), cyan (C), and black (K) toner patterns using threshold signals. The CPU 109 corrects the color misregistration by controlling the writing timing of the optical scanning device 15 via the optical scanning device control unit 112 based on the detected amount of color misregistration.

[0035] (Density detection pattern image) Next, the density detection pattern image formed on the intermediate transfer belt 5 when the CPU 109 performs density detection will be described. FIG. 6 is a diagram showing the density detection pattern image. FIG. 6(a) is a diagram showing a first density detection pattern image 601 formed on the intermediate transfer belt 5 for toner density detection. The first density detection pattern image 601 is used by the first PD 71 to receive specularly reflected light of light emitted from the first LED 73. The first density detection pattern image 601 is formed with black (K) toner and is used when performing black (K) toner density detection. Black (K) has the property of absorbing light and cannot be detected by diffusely reflected light, so toner density detection is performed using the detection result of the first PD 71, which receives specularly reflected light.

[0036] 6(a) is formed of four gradation patterns, with the density levels being 70%, 50%, 30%, and 10%, in descending order of density. The CPU 109 reads the first density detection pattern image 601 formed on the intermediate transfer belt 5 with the pattern sensor 7 and obtains a first detection signal P1 from the first PD 71. The CPU 109 converts the first detection signal P1 into a digital signal with the A / D converter 110, calculates the difference between the value of the digital signal and the image density gradation characteristics to be actually output, and performs density correction by controlling the image formation control unit 120 based on the calculation result.

[0037] FIG. 7 is a diagram showing the output waveform of the pattern sensor 7 that detected the first density detection pattern image 601. In the 70% area, which is a high density, light from the first LED 73 is absorbed by the black (K) toner, and the amount of black (K) toner carried is large, so the amount of specularly reflected light from the intermediate transfer belt 5 is also reduced. Therefore, the reading level of the 70% area, which is a high density, is low. On the other hand, in the 10% area, which is a low density, the amount of light absorbed by the black (K) toner is lower than the amount of light absorbed by the 70% area, and the amount of black (K) toner carried is small, so the amount of specularly reflected light from the intermediate transfer belt 5 is increased. Therefore, the reading level of the 10% area, which is a low density, is high. In the non-pattern area NP, the first density detection pattern image 601 is not formed, so there is a lot of specularly reflected light from the intermediate transfer belt 5, and so the reading level is high.

[0038] FIG. 6B shows a second density detection pattern image 602 formed on the intermediate transfer belt 5 for toner concentration detection. The second density detection pattern image 602 is used to receive diffusely reflected light from the second LED 74 using the second PD 72. The second density detection pattern image 602 is formed using yellow (Y) toner, magenta (M) toner, and cyan (C) toner, and is used to perform yellow (Y) toner concentration detection, magenta (M) toner concentration detection, and cyan (C) toner concentration detection. FIG. 6B shows the second density detection pattern image 602 formed using toner of one color among yellow (Y), magenta (M), and cyan (C). Because yellow (Y), magenta (M), and cyan (C) have a higher diffuse reflectance than the intermediate transfer belt 5, toner concentration detection is performed using the detection results of the second PD 72 that receives diffusely reflected light.

[0039] 6(b), the second density detection pattern image 602 is formed with four gradation patterns, with the density levels being 70%, 50%, 30%, and 10%, in descending order of density. The CPU 109 reads the second density detection pattern image 602 formed on the intermediate transfer belt 5 with the pattern sensor 7, and obtains a second detection signal P2 from the second PD 72. The CPU 109 converts the second detection signal P2 into a digital signal with the A / D converter 110, calculates the difference between the value of the digital signal and the image density gradation characteristics to be actually output, and performs density correction by controlling the image formation control unit 120 based on the calculation result.

[0040] FIG. 8 shows the output waveform of the pattern sensor 7 detecting the second density detection pattern image 602. This example illustrates the case where the second density detection pattern image 602 is formed with yellow (Y) toner. In the 70% area, which is a high density, light from the second LED 74 is reflected by the yellow (Y) toner. Furthermore, since the amount of yellow (Y) toner carried is large, the amount of diffused light from the yellow (Y) toner also increases. Therefore, the read level of the 70% area, which is a high density, is high. On the other hand, in the 10% area, which is a low density, the reflectance of the yellow (Y) toner is lower than that of the 70% area, so the amount of diffused light is reduced. Therefore, the read level of the 10% area, which is a low density, is low. In the non-pattern area NP, the second density detection pattern image 602 is not formed, and therefore there is less diffused light reflected from the intermediate transfer belt 5, so the read level is low. The magenta (M) toner and cyan (C) toner density detection is performed in the same manner as the toner density detection of yellow (Y) toner.

[0041] (Fixed unit) Next, the fixed unit 17 to which the three pattern sensors 7 are attached will be described with reference to FIG. 9. FIG. 9 illustrates the fixed unit 17 to which the pattern sensors 7 are attached. FIG. 9(a) is a side view of the fixed unit 17 as viewed from the direction indicated by the arrow IXA in FIG. 1. The direction indicated by the arrow IXA is the direction opposite to the moving direction R1 of the intermediate transfer belt 5. The fixed unit 17 has an elongated shape extending in the main scanning direction MS, which is perpendicular to the moving direction R1 (i.e., the sub-scanning direction SS) of the intermediate transfer belt 5. The intermediate transfer belt 5 is disposed in the direction opposite to the direction indicated by the arrow Z (the negative direction), i.e., on the lower side of FIG. 9(a). Three pattern sensors 7 are fixed to the fixed unit 17 by screws 21, which serve as fixing means, aligned in the main scanning direction MS. The three pattern sensors 7 detect the color misregistration detection pattern image 401, the first density detection pattern image 601, and the second density detection pattern image 602 formed on the intermediate transfer belt 5.

[0042] The reason for arranging the three pattern sensors 7 side by side in the main scanning direction MS is to detect the amount of color misregistration that varies depending on the main scanning position by detecting the three color misregistration detection pattern images 401 formed side by side in the main scanning direction MS, and also to shorten the control time for density detection by detecting the three second density detection pattern images 602 of three colors formed side by side in the main scanning direction MS with the three pattern sensors 7, respectively.

[0043] The reason why pattern sensor 7 is fixed to fixing unit 17 is to improve assembly. Pattern sensor 7 is placed at a rear position inside image forming apparatus 100 in order to detect the pattern image formed on intermediate transfer belt 5. Here, rather than fixing three pattern sensors 7, which are relatively small components, separately at rear positions inside image forming apparatus 100, fixing fixing unit 17, to which three pattern sensors 7 are fixed in advance, at a rear position inside image forming apparatus 100 improves assembly.

[0044] Three openings 17a are provided on a side surface 17s of the fixed unit 17, corresponding to the three pattern sensors 7 fixed to the fixed unit 17. When viewed from the direction indicated by arrow IXA in FIG. 1, a part of the connector 205 can be seen through the openings 17a.

[0045] FIG. 9(b) is a plan view of the fixed unit 17 as viewed from the direction indicated by the arrow IXB in FIG. 1. The sub-scanning direction SS is parallel to the movement direction R1. Three openings 17c are provided in the top surface 17t of the fixed unit 17, corresponding to the three pattern sensors 7 fixed to the fixed unit 17. The openings 17c are through-holes that penetrate from the top surface 17t to the bottom surface 17b of the fixed unit 17. The connector 205 is inserted into the opening 17c. When viewed from the direction indicated by the arrow IXB in FIG. 1, the connector 205 can be seen through the opening 17c. As shown in FIG. 9(b), the opening 17c communicates with the opening 17a.

[0046] FIG. 9(c) is an end view of the fixing unit 17 as viewed from the direction indicated by the arrow IXC in FIG. 9(a). The back surface (second surface) 201b of the substrate 201 of the pattern sensor 7 is in contact with the bottom surface (reference surface) 17b of the fixing unit 17. FIG. 9(d) is a cross-sectional view of the fixing unit 17 taken along the line IXD-IXD in FIG. 9(a). To increase rigidity, the portion of the fixing unit 17 not in contact with the pattern sensor 7 has a thickness (second thickness) H in the Z direction (the insertion / removal direction of the cable 300) based on the bottom surface (reference surface) 17b of the fixing unit 17. However, as shown in FIGS. 9(a) and 9(d), the thickness of the fixing unit 17 is thinner on the downstream side in the sub-scanning direction SS near the pattern sensor 7. This improves the visibility of the connector 205 and the ease of inserting and removing the cable 300 from the connector 205 when viewed from the direction indicated by the arrow IXA in FIG. 1.

[0047] 9(d), a portion 17e (a bottom portion corresponding to the opening 17a) of the fixing unit 17 corresponding to the bottom surface 17b of the fixing unit 17 that contacts the substrate 201 of the pattern sensor 7 has a thickness (first thickness) h_u in the insertion / removal direction (direction indicated by arrow Z) of the cable 300. In the insertion / removal direction of the cable 300, the thickness (first thickness) h_u of the portion 17e of the fixing unit 17 that contacts the back surface 201b of the substrate 201 is thinner than the thickness (second thickness) H of the portion of the fixing unit 17 that does not contact the back surface 201b of the substrate 201. The portion 17e of the fixing unit 17 having the thickness (first thickness) h_u is within the range of the width W of the substrate 201 in the longitudinal direction, as shown in FIG.

[0048] A thickness h_u of a part 17e of the fixed unit 17, based on the bottom surface 17b in the insertion / removal direction of the cable 300 (the direction indicated by the arrow Z), is thinner than a height h_c of the connector 205 of the pattern sensor 7. This allows the connector 205 to be seen without being hidden by the fixed unit 17 when the fixed unit 17 is viewed from the downstream side in the sub-scanning direction SS. Furthermore, since there is an opening 17a communicating with the opening 17c through which the cable 300 passes when connecting the cable 300 to the connector 205, interference of the hand holding the cable 300 with the top surface 17t of the fixed unit 17 can be reduced, improving workability. In this embodiment, the thickness h_u of the bottom portion corresponding to the opening 17a of the fixed unit 17 is two-thirds or less of the height h_c of the connector 205.

[0049] In this embodiment, the fixing unit 17 is attached to the image forming apparatus 100 from the downstream side in the sub-scanning direction SS, and therefore the thickness h_u of the bottom portion on the downstream side of the fixing unit 17 is made small. However, when the fixing unit 17 is attached to the image forming apparatus 100 from the upstream side in the sub-scanning direction SS, the thickness of the bottom portion on the upstream side of the fixing unit 17 may be made small to improve the visibility of the connector 205 and the ease of inserting and removing the cable 300.

[0050] 9(d), in order to increase the rigidity of the portion of the fixing unit 17 near the connector 205, the fixing unit 17 is provided with a wall 17d. The wall 17d reinforces the strength of a portion 17e of the fixing unit 17 having a thickness (first thickness) h_u. According to this embodiment, the strength of the fixing unit 17 is maintained while improving the visibility of the connector 205 of the pattern sensor 7 and the ease of inserting and removing the cable 300, thereby improving the quality of assembling the fixing unit 17 to the image forming apparatus 100.

[0051] According to the first embodiment, the rigidity of the fixed unit 17 is maintained while the visibility of the connector 205 of the pattern sensor 7 is improved, thereby facilitating the connection of the connector 205 and the cable 300. [Example]

[0052] A second embodiment will be described below. In the second embodiment, the same structures as those in the first embodiment are given the same reference numerals and will not be described again. The image forming apparatus 100 and the pattern sensor 7 in the second embodiment are the same as those in the first embodiment, and therefore their description will be omitted. The fixed unit 170 in the second embodiment differs from the fixed unit 17 in the first embodiment in that it does not have a wall portion 17d. The following description will mainly focus on the differences.

[0053] FIG. 10 illustrates a fixing unit 170 according to a second embodiment. FIG. 10(a) is a side view of the fixing unit 170. FIG. 10(b) is a plan view of the fixing unit 170. One side surface 170s1 of the fixing unit 170 is provided with three openings 170a1 corresponding to the three pattern sensors 7 fixed to the fixing unit 170. The other side surface 170s2 of the fixing unit 170 is also provided with three openings 170a2 corresponding to the three pattern sensors 7 fixed to the fixing unit 170. The bottom surface 170b of the fixing unit 170 is provided with three openings 170c corresponding to the three pattern sensors 7 fixed to the fixing unit 170. When viewed along the sub-scanning direction SS, a portion of the connector 205 can be seen through the openings 170a2. When viewed in the direction opposite to the sub-scanning direction SS, a portion of the connector 205 can be seen through the openings 170a1.

[0054] FIG. 10(c) is an end view of the fixing unit 170 as viewed from the direction indicated by the arrow XC in FIG. 10(a). FIG. 10(d) is a cross-sectional view of the fixing unit 170 taken along the line XD-XD in FIG. 10(a). To enhance rigidity, the fixing unit 170 has a thickness H in the Z direction as shown in FIGS. 10(c) and 10(d). However, as shown in FIGS. 10(a) and 10(d), the fixing unit 170 is thinner on the upstream and downstream sides in the sub-scanning direction SS near the pattern sensor 7. This improves the visibility of the connector 205 when viewed in the sub-scanning direction SS and the direction opposite to the sub-scanning direction SS, as well as the ease of inserting and removing the cable 300 from the connector 205.

[0055] 10(d), a thickness h_u of a portion of the fixed unit 170 corresponding to the bottom surface (reference surface) 170b that contacts the substrate 201 of the pattern sensor 7 is thinner than a height h_c of the connector 205 of the pattern sensor 7. This allows the connector 205 to be seen without being hidden by the fixed unit 170 when the fixed unit 170 is viewed from the upstream or downstream side in the sub-scanning direction SS. Furthermore, since there are openings 170a1 and 170a2 that communicate with opening 170c through which the cable 300 passes when connecting the cable 300 to the connector 205, it is possible to reduce interference between the hand holding the cable 300 and the top surface 170t of the fixed unit 170, improving workability.

[0056] According to the second embodiment, the rigidity of the fixing unit 170 is maintained while the visibility of the connector 205 of the pattern sensor 7 is improved, thereby facilitating the connection of the connector 205 and the cable 300.

[0057] In the first and second embodiments, the pattern sensor 7 is disposed near the intermediate transfer belt 5 and detects the pattern image formed on the intermediate transfer belt 5. However, the pattern sensor (optical sensor) 7 may be disposed near the photosensitive drum (image carrier) 1 and detect the pattern image formed on the photosensitive drum 1. In the first and second embodiments, multiple pattern sensors 7 are fixed to the fixing units 17 and 170, but at least one pattern sensor 7 may be fixed to the fixing units 17 and 170. [Explanation of symbols]

[0058] 1. Photosensitive drum 5. Intermediate transfer belt 7. Pattern sensor 17, 170... Fixed unit 17b, 170b...bottom 71. First PD 72...Second PD 73 First LED 74...Second LED 100 Image forming device 201... Substrate 201a...Surface 201b...Back side 205···Connector H: Second thickness h_u First thickness

Claims

1. an image carrier; a sensor for detecting a pattern image formed on the image carrier; a mounting member to which the sensor is attached; Equipped with The sensor A substrate; a light-emitting element provided on a first surface of the substrate; a light receiving element provided on the first surface of the substrate; a connector provided on a second surface of the substrate opposite the first surface; Equipped with The mounting member is a third surface having an opening into which the connector of the sensor is inserted; a fourth surface perpendicular to the third surface and parallel to the longitudinal direction of the mounting member; a part of the fourth surface of the mounting member is cut out so that the connector can be easily seen when viewed from one direction perpendicular to the longitudinal direction of the mounting member and parallel to the first surface of the sensor attached to the mounting member; The width of the cutout portion of the fourth surface in the longitudinal direction of the mounting member is wider than the width of the connector inserted into the opening in the longitudinal direction of the mounting member. An image forming apparatus characterized by:

2. The sensor is fixed to the mounting member with a screw, 2. The image forming apparatus according to claim 1, wherein the connector is located between two screws in the longitudinal direction of the board.

3. 3. The image forming apparatus according to claim 2, wherein the cutout portion of the mounting member is located between the two screws in the longitudinal direction of the board.

4. 4. The image forming apparatus according to claim 1, wherein the height of the connector in the direction perpendicular to the board is lower than the height of the mounting member in the direction perpendicular to the board.

5. a substrate; a light-emitting element provided on a first surface of the substrate; a light-receiving element provided on the first surface of the substrate; and a connector provided on a second surface of the substrate opposite to the first surface; a sensor comprising: a mounting member to which the sensor is attached, The mounting member is a third surface having an opening into which the connector of the sensor is inserted; a fourth surface perpendicular to the third surface and parallel to the longitudinal direction of the mounting member; a part of the fourth surface of the mounting member is cut out so that the connector can be easily seen when viewed from one direction perpendicular to the longitudinal direction of the mounting member and parallel to the first surface of the sensor attached to the mounting member; An optical detection device characterized in that the width of the cutout portion of the fourth surface in the longitudinal direction of the mounting member is wider than the width of the connector inserted into the opening in the longitudinal direction of the mounting member.

6. The sensor is fixed to the mounting member with a screw, 6. The photodetector according to claim 5, wherein the connector is located between two screws in the longitudinal direction of the substrate.

7. 7. The photodetector according to claim 6, wherein the cutout portion of the mounting member is located between the two screws in the longitudinal direction of the substrate.

8. 8. The light detection device according to claim 5, wherein the height of the connector in the direction perpendicular to the board is lower than the height of the mounting member in the direction perpendicular to the board.

9. a substrate; a light-emitting element provided on a first surface of the substrate; a light-receiving element provided on the first surface of the substrate; and a connector provided on a second surface of the substrate opposite to the first surface; A mounting member to which a sensor comprising: a third surface having an opening for inserting the connector of the sensor; a fourth surface perpendicular to the third surface and parallel to the longitudinal direction of the mounting member; a cutout portion of the fourth surface of the mounting member so that the connector can be easily seen when viewed from one direction perpendicular to the longitudinal direction of the mounting member and parallel to the first surface of the sensor attached to the mounting member; and and A mounting member characterized in that the width of the cutout portion of the fourth surface in the longitudinal direction of the mounting member is wider than the width of the connector inserted into the opening in the longitudinal direction of the mounting member.

10. A plurality of screw holes are formed for fastening the sensor with screws, The mounting member according to claim 9, wherein the opening is located between a first screw hole included in the plurality of screw holes and a second screw hole included in the plurality of screw holes.

11. 11. The mounting member according to claim 10, wherein the cutout portion is located between the first screw hole and the second screw hole.

Images